The present work combines the solar energy with the environmental protection through the membrane selectivity for metallic ions. Firstly, we have elaborated new polymeric membranes for ions separation. The membrane is made up of cellulose acetate (CA) modified by polyelectrolytes (polyethylenimine (PEI), polyvinyl alcohol (PVA) and polyanetholsulfonic acid (PATSA) using glycerol as plasticizer. Different membranes are characterized by Fourier transform infrared spectroscopy (FTIR), X‐Ray diffraction (XRD), thermo‐gravimetric analysis (TGA) and scanning electron microscopy (SEM). In a second part, we have prepared two new photo‐electrodes, crystallizing in the brownmillerites structure: n‐Sr2Fe2O5 and p‐Sr2Co2O5 and their photo‐electrochemical characterizations are undertaken. As application, the transport of Cd2+ using the synthesized membranes coupled with the photo‐electrodes is studied. The photo‐catalytic results indicate that the combined hetero‐system n‐Sr2Fe2O5/p‐Sr2Co2O5 enhances considerably the electrons transfer. The diffusion flux of Cd2+ is considerably enhanced when the electrode is exposed to visible light illumination. The results show that the transport percentages of Cd2+ increases by 40% under solar energy and 25% under a tungsten lamp.